Most of the methods for producing wash-free rice employ washing (by water) steps (i.e. wet processes). However, some methods employ dry processes. One of such dry processes disclosed in Japanese laid open patent No.2001-286773 (hereinafter referred as Ref.1) is invented to provide a simply structured compact waterless rice washing apparatus which can be constituted at a low cost and be used by small food service industries, restaurants, hotels, hospitals and the like. The disclosed waterless rice washing machine comprises supply units for supplying polished rice and interposing matter to be mixed with the rice, a rice washing container for accommodating a mixture of the polished rice and the interposing matter and a separating unit for separating pure polished rice, the interposing matter and bran from the washed mixture, wherein: the supply units are arranged above the rice washing container, the separating unit is arranged below the rice washing container and a plurality of baffle plates are arranged in the rice washing container.
Japanese laid open patent No.2001-96177 (hereinafter referred as Ref.2) discloses polished rice washing apparatus which can remove oxidized layers and bran layers formed on the surfaces of polished rice grains, and bran deposited in grooves of polished rice grains without damaging the surfaces of polished rice grains. The disclosed polished rice washing apparatus comprise a rice inlet, a rice polishing chamber, a pair of rice polishing plates in which brushes are buried, a cover for preventing rice from spilling out of the rice polishing plates, a driving means for driving the polishing plates, another cover for preventing bran from spilling out of the rice polishing chamber and a polished rice outlet, wherein: the rice inlet and the rice outlet are communicated each other via the rice polishing chamber, the rice polishing plates are arranged inside of the rice polishing chamber such that tips of the brushes respectively arranged on the rice polishing plates are directed to each other and the cover for the polishing plates are perforated. The apparatus obtained by the disclosed invention can remove oxidized layers and bran layers formed on the surfaces of polished rice grains and bran deposited in grooves of polished rice grains by brushes arranged in the upper part and lower part of the apparatus without damaging the surfaces of polished rice grains.